Charging?

I have a voltmeter plugin in the cig lighter socket. It reads about 11.5 when
I trun on the master. Reads about 12.8 after engine start and after an hour
flight has worked up to maybe 13.7 or so. I plan on taking a known accurate
meter out Sat to check these reading.
My A&P says maybe the alternator needs rebuilt (at about $250). He says that
the voltage reg is solid state and either works or not - ie no adjustment.
I've had a couple of times when the bat needed a boost, so something is wrong.
Any comments before I start throwing money at the problem.

Chuck
Archer 2185B

PaulaJay1 wrote:
I have a voltmeter plugin in the cig lighter socket. It reads about
11.5 when
I trun on the master. Reads about 12.8 after engine start and after
an hour
flight has worked up to maybe 13.7 or so. I plan on taking a known
accurate
meter out Sat to check these reading.
My A&P says maybe the alternator needs rebuilt (at about $250). He
says that
the voltage reg is solid state and either works or not - ie no
adjustment.
I've had a couple of times when the bat needed a boost, so something
is wrong.
Any comments before I start throwing money at the problem.


Put a voltmeter on the battery with the master off. It should be
reading above 12 volts (mine reads ~12.4V) if it's fully charged. I
always see at least 12 volts on the bus and cigarette lighter before I
start. The fact that your voltage is slowly working its way up to
normal (should be around 14V), would lead me to think that the problem
may be that the battery is slow to take a charge.

Before tearing into the alternator, which appears to be generating
some electricity, I'd pull the battery, put it on a charger, then see
if it will hold itself above 12V. If not, it's time for a new battery.
John Galban=====N4BQ (PA28-180)

On 27-Jan-2005, (PaulaJay1) wrote:

Any comments before I start throwing money at the problem.


Pardon if this sounds overly obvious, but have you verified that the
alternator belt is nice and tight (and not deteriorated)? A worn and/or
slipping belt could easily give you these symptoms.

Speaking of alternator belts, our mechanic did something very clever for us
that might be of interest to others. When he installed our new engine some
months ago, he tie-wrapped a spare belt up against the engine, around but
well behind the flywheel. The idea is that if we suffer a broken alternator
belt the spare can be put on in a matter of minutes, with no special tools,
and without having to take off the prop. Anybody else use this trick?

--
-Elliott Drucker

I would think the heat from the engine would raise a havoc with the belt..
and it might smell pretty bad it gets hot
BT

wrote in message
news:U7gKd.1200$Pr4.896@trnddc03...

On 27-Jan-2005, (PaulaJay1) wrote:

Any comments before I start throwing money at the problem.


Pardon if this sounds overly obvious, but have you verified that the
alternator belt is nice and tight (and not deteriorated)? A worn and/or
slipping belt could easily give you these symptoms.

Speaking of alternator belts, our mechanic did something very clever for
us
that might be of interest to others. When he installed our new engine
some
months ago, he tie-wrapped a spare belt up against the engine, around but
well behind the flywheel. The idea is that if we suffer a broken
alternator
belt the spare can be put on in a matter of minutes, with no special
tools,
and without having to take off the prop. Anybody else use this trick?

--
-Elliott Drucker

Chuck,
You need to also measure the current the alternator is putting out at
the same time. The voltage alone will not tell the whole story.
If the alternator is putting out and the voltage is still low then there
is a big draw on the system. Likely the battery. Once it is satisfied
then the buss voltage will rise. The comment about the regulator is BS.
Likely from someone who does not understand them. They are adjustable.
13.7 is only slightly low for a 14V system. it should be 13.8-14.2.
If you can get a recording meter like a Fluke that would be best. If you
can get one that will do both AC and DC at the same time, this would be
good as well. This will tell you if a diode or two has or is dying.
Michelle

PaulaJay1 wrote:

I have a voltmeter plugin in the cig lighter socket. It reads about 11.5 when
I trun on the master. Reads about 12.8 after engine start and after an hour
flight has worked up to maybe 13.7 or so. I plan on taking a known accurate
meter out Sat to check these reading.
My A&P says maybe the alternator needs rebuilt (at about $250). He says that
the voltage reg is solid state and either works or not - ie no adjustment.
I've had a couple of times when the bat needed a boost, so something is wrong.
Any comments before I start throwing money at the problem.

Chuck
Archer 2185B

Michelle P writes:

Chuck,
You need to also measure the current the alternator is putting out at
the same time. The voltage alone will not tell the whole story.
If the alternator is putting out and the voltage is still low then there
is a big draw on the system. Likely the battery. Once it is satisfied
then the buss voltage will rise. The comment about the regulator is BS.
Likely from someone who does not understand them. They are adjustable.
13.7 is only slightly low for a 14V system. it should be 13.8-14.2.
If you can get a recording meter like a Fluke that would be best. If you
can get one that will do both AC and DC at the same time, this would be
good as well. This will tell you if a diode or two has or is dying.
Michelle

I second the line of thinking. Make more measurements. Use a scope
to look for bad diodes. Use a good DVM to measure the alternator
OUTPUT at the alternator. Big issue here is keeping body parts out
of the way of the people-chopper up front as you must be well above
idle.

Bad diodes are about the only {alternator} thing that keeps an
alternator+regulator+installation from making full output. Most of
the time, it's regulator or loose wiring issues that bite you on
the [banned by Mikey Powell]... err tailwheel.

GM auto alternators have a "full-field" tab. It lets you bypass
the regulator so you can see the alternator working full tilt.
This typically gets you 15+ volts DC, so if such can be done,
pull all the avionics feeds first......

In a car, I think the best belt test is your ears. Load the alternator
with headlights/blowers/heated seats etc. The belt should talk to
you but not howl/sing. I don't know if you can hear as well w/
aircraft.


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On 27-Jan-2005, "BTIZ" wrote:

I would think the heat from the engine would raise a havoc with the belt..
and it might smell pretty bad it gets hot


The "spare" belt is positioned in a way that it is well clear of the
cylinders and heads. Actually, the belt doesn't even contact the crankcase
that much, and the case doesn't get particularly hot. The mechanic says his
shop has been doing this for a while now with no problems.
--
-Elliott Drucker

Mostly anybody who has worked on a Lycoming in the last thirty years.

Jim



The idea is that if we suffer a broken alternator
belt the spare can be put on in a matter of minutes, with no special
tools,
and without having to take off the prop. Anybody else use this trick?

--
-Elliott Drucker

The "spare" belt is positioned in a way that it is well clear of the
cylinders and heads. Actually, the belt doesn't even contact the
crankcase
that much, and the case doesn't get particularly hot. The mechanic says
his
shop has been doing this for a while now with no problems.

I, for one, think it's a fabulous idea.

I wish more shops would think proactively like this.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Hmmm, My solid state regulator has an adjustment under a screw that is
removed. I believe it even has arrows to show increase/decrease
direction.

PaulaJay1 wrote:

I have a voltmeter plugin in the cig lighter socket. It reads about 11.5 when
I trun on the master. Reads about 12.8 after engine start and after an hour
flight has worked up to maybe 13.7 or so. I plan on taking a known accurate
meter out Sat to check these reading.
My A&P says maybe the alternator needs rebuilt (at about $250). He says that
the voltage reg is solid state and either works or not - ie no adjustment.
I've had a couple of times when the bat needed a boost, so something is wrong.
Any comments before I start throwing money at the problem.

Chuck
Archer 2185B